Method of protecting underground pipes and conduits



July 16, 9 v. A. GRODSKY METHOD OF PROTECTING UNDERGROUND PIPES AND CONDUITS Filed Oct. 14, 1953 pants; i 1a, was. I e 2,007,969

UNITED STATES PATENT OFFICE METHOD OF PROTECTING PIPES AND CONDUITS Vladimir a. Grodsky, nu, Church, va. Application October 14, 1933, Serial No. seam 4 (CI. 61-72) The present invention relates to a method of I find as a result of my invention that a thin protecting metal conduits, such as metal pipes film, resistant to the effects of oxidation and against soil corrosion. corrosive influences, is formed on the pipe or con- Heretofore in the case of cast and wrought iron duit. This film is microscopic in character and 5 pipes, numerous expedients have been employed is continuously formed, so that should it be 5 to overcome the corrosive tendencies. Generally broken at any point, the break is immediately the means utilized has consisted of a wrapping healed. a or coating of the pipe with some resistant mate- I furtherfind as a result of my invention that rial which is expensive and has not been sufli-, the corrosive influences active in the presence of 1 ciently protective. moisture, in acid soil or soil containing potential My method therefore aims to provide a. proacid forming salts are corrected and rendered tective for the pipes which takes into considerasubstantially innocuous. tion the various soils in which pipes and con- In the accompanying drawing, duits are usually disposed and without regard to Figure 1 is a sectional view showing one form I5 locality. Stated briefly, the present invention is of the invention, applicable in the case of acid soils which pre- Figure 2 is a sectional view showing another dominate in the East, as well as alkali soils which form of the invention, are to be found in the central and western por- Figure 3 is a perspective view showing the form tions of the United States, and I prepare the of the invention shown in Figure 2 with the ensoil in such a manner that the corrosive infiuveloping flap overlying the pipe, and 20 ances present are neutralized and rendered in- Figure 4 is a view partly in section illustrating nocuous. This is accomplished preferably by in detail the manner in which a portion of the mixing a portion of the soil removed from the envelope is folded over the pipe and the soil entrench or excavation with a proper percentage of closing the same.- an inhibiting compound usually an alkali, where- Referring to the drawing, I have indicated at 25 by the acidity is neutralized in the case of acid ill a pipe which may be of cast iron, wrought iron, soils, and the potential acidity isbalanced in the or pipes or conduits of other metals, such as case of alkaline soils. The soilas conditioned will usually employed in underground conduits for comprise a small percentage of the total earth water mains, gas mains,-pipe lines and electrical removed from the trench or excavation and is transmitting wires. returned in its loose absorbent condition to the The pipe as shown is disposed in anexcavation trench. in the usual manner to fill the same and or trench II which is dug in the usual manner coverthe pipe. I i and a portion of the earth removed therefrom, is

I find it desirable and economical to isolate the first tested to determine its chemical nature. portion of the soil so conditioned and returned Thereafter, a suitable waterproof fabric which 35 to the trench for two reasons. First, by isolating may be textile or paper-like, indicated at H, is the conditioned soil from the remainder of the placed in the trench and forms a lining for the adjacent soil it is possible to maintain a substan-- same, as shown. This lining will be in the form tially. constant mixture. Again, by isolating or of strip material and the ends of the strip lengths confining the conditioned soil with positive means, are overlapped and a 'suitable waterproof joint I prevent any possibility of the leaching out of provided, as by means of a coating of asphalt the neutralizing agent due to the presence of or similar moisture resistant material, as shown excess water. at-ll'. The means which I employ to accomplish this The conditioned soil, 1. e.; a small portion of the 45 isolation will preferably comprise a waterproof total earth removed from the trench and summaterial, such as textile or paper fabric, providcient to surround the pipe, is indicated at l3 ing a liner in the lower portion of the trench, forming a covering layer. and in some cases forming an envelope to com 'The soil having been removed and its nature pletely isolate the pipe and conditioned soil. determined, I add thereto one or more of a group Instead of conditioning the soil by mixing a of corrosion inhibiting compounds selected from neutralizing agent therewith, I in some cases the oxides, hydroxides and carbonates of the provide the pipe or conduit with a surrounding alkali metals or alkali earth metals. I prefer to layer of the neutralizing or inhibiting agent,.and use calc m wd i e u Sodium hydroxide d preferably enclose the loose absorbent mass in potassium hydroxide ay be p d, 8 W l as an envelope of the lining material. calcium oxide, barium oxide. calcium and barium Phosphorus and chromium compounds may also be employed. As an economical and effective neutralizing i. e.,

' corrosion inhibiting agent, ordinary lime, crushed limestone or burnt lime may be used with advantage.

In order to condition the soil, a suflicient portion thereof to surround the pipe or conduit with a covering layer of the mixture to a depth which will be protective, is suitably mixedwith one or a mixture of the above mentioned compounds in proper percentage in relation to the acidity or potential acidity of the soil 1. e., in amount-to neutralize and correct the corrosive influences of the soil on the metal conduit or pipe. Thereafter the pipe and the loose absorbent conditioned soil are placed in the trench in the manner illustrated in the drawing, whereby the pipe is provided with a surrounding or enclosing layer of the conditioned soil which will protect it against corrosive corrosive influences and oxidation take place in the presence of moisture or water.

The presence of the alkali in the case of acid soils tends to eliminate or inhibit oxidation and to neutralize the acidity and'hence reduces the corrosive influences. In the case of alkaline soils 7 containing compounds such as chlorides and sul phates, hydrolizing in the-presence of water, the addition of the conditioning agents to the soil mixture will tend to neutralize andperhaps prevent or' inhibit. chemical action, such as will induce corrosion. h The lining or envelope l2, as stated, is waterproof and will prevent the leaching out of the neutralizing or inhibiting compound added to the conditioned soil as, for instance, in the presence of an excess amount of water, and this lining or envelope moreover isolates and confines the pipe and the surrounding protective layer from the remainder of the soil to likewise insure that the constancy of the protective effect maintained. That is to say, by segregating and confining the layer of conditioned material from the remainder of the soil, either by a partially closed lining, as shown in Figure 1, or a com,-

pletely enclosing envelope, as shown in Figure 4,

the mixture is confined and the constancy of the Y mixture and its protective qualities are assured.

It should be borne in mind that usually the rel of soil constituting the protective soil corrosion comprising preparing a trench to ative quanti layer is smallwith respect to the total amount ofwthat excavated.

- lnFigurezlhave shown the lining l2 ashav-- ing a long side I which, as shewn in Figures 3 and 4, is folded over to form a continuous seal about the pipe and the conditioned layer imme-' diately surrounding it. This is desirable in some cases, lthough it is not essential and the ends 'of the nvelope are overlapped as shown in Figure 4 and provided with -a waterproof seal by means of a suitable composition, such as indicated at Ii. I

While I have described-a conditioning 'of the es asphalt,

' soil and forming the same into a protective layer. 76 about the pipe or conduit, 1 will also in some 7 I 2,007,969 bicarbonate, and in some cases, sodium carbonate.

cases, and in lieu of a conditioned soil layer, provide the pipe or conduit with a layer of the con- 1 ditioning agent only. That is to say, the pipe or conduit will be surrounded and buried in ,the loose absorbent mass ofone or a mixture of the several conditioning agents above referred to. Where I resort to the use of the neutralizing i. e. inhibiting agents alone, instead of a mixture thereof with the soil, I also employ the isolating or confining means in the nature of the lining l2 and preferably utilize the enclosing envelope, as shown in Figure 4. As stated, this envelope will isolate the protective layer from the soil and prevent any leaching or. loss of the neutralizing agent due to the presence of water or seepage.

' Theamount of neutralizing or inhibiting agent mixed with the soil to condition the same will, of course, vary with the particular earth and surrounding conditions and circumstances affecting the installation. Likewise, the thickness of the loose absorbent layer will be varied in accordance with requirements. a

The primary purpose of the invention, as will be understood from the above description, is to produce about a pipe or conduit a condition of neutralization ofthe corrosive influences which are present either actually or potentially in the soil and which, by reason of the presence of moisture or water promote chemical action and oxidation. That is, corrosion inhibiting reagents are employed with or without admixture with soll forming a loose covering layer which is absorbent. This layer is confined by the liner.

My invention afi'ords a very economical means of protecting pipes used in various underground condu ts since all that is necessary is to condition the soil by mixing the inhibiting or neutralizing agent therewith. The protective condition is constantly maintained by the presence of the isolating or confining lining which serves to maintain the consistency of the mixture and prevent any loss of the reagent. j

Although a number of compounds to be, employed as conditioning agents have been ted above, I do not limit myself to any of these ce others and equivalent compounds may be employed and found useful under the particular circumstances.

Iclaim:

L'The method of protecting conduits against sofl corrosion comprising preparing a trench to receive the conduit, disposing a waterproof liner in said trench, placing a conduit in the trench andwithin'the confinesof said liner, forming between the conduitand liner a'neutralized soil covering layer, and confining said covering layer by said liner to prevent deterioration of the neutralized soil.

2. The method of protecting conduits against receive the conduit, disposing a waterproof liner in said trench, placing a-conduit in the trench and within. the confines of said liner, neutralizing a portion of the soil removed from the trench,

placing said neutralized soil between the conduit 1 and the liner to form a soil covering layer, and confining said covering layer by said liner to prevent deterioration of the neutralized soil.

3. A co'nduitinstallation comprising-a metal conduit, a layer of loose material, containing a corrosion inhibiting chemical reagent, surrounding said conduit, and .a confining means enclosing said layer of loose material.

4. The method ortpmtecnn conduits against moved from the trench with an alkaline comsoil corrosion in acid soils comprising preparing 7 pound, placing said alkali treated soil between a trench to receive the conduit, disposing a the conduit and the liner to form a soil covering waterproof liner in said trench, placing a conlayer, and confining said covering layer by said 5 duit in the trench and within the confines of liner to prevent deterioration of the treated soil. 5

said liner, combining a portion of the soil re- VLADIMIR A. GRODSKY. 

